So about 2 months ago i bought a 05 f-350 with 156k miles, it has a bad shake (up and down, not side to side) when its at about 50 and above and the Torque converter locks, kind of goes away after lockup but its hard to tell because there isnt a perfectly smooth road around so i dont know if its even the truck making it shake. seems that the shake isnt as bad when coasting down. no shaking going downhill or under mild load (even if TC stays locked) It only happens when Cruise is set, or under slight acceleration. doesnt happen in TOW/HAUL mode or its just not noticeable.

there is no smoke at all, ive tried everything but brake-torquing and still no smoke. boost peaks at 22psi on stock gauge.

stuff that it isnt(already verified, replaced, etc):
alternator was replaced the day i bought it
has new tires balanced with alignment
replaced ficm due to low voltage yesterday
dealer did a contribution test, said all inj good
oil change with Motorcraft oil and filters.
fuel filter change
blue spring kit
latest pcm and ficm program from ford
EDIT: CAC boots are good, replaced 1 and the others were pretty new looking.

1. my understanding is that the TC stays locked in tow/haul so im leaning towards the tc being ok, as the rpm gauge doesnt move when vibrating.

2. dealer pulled P0404 and P0408 for egr valve and say that even with cooler delete that it will cause these problems(they also said my turbo had a wastegate so i dont trust their knowledge too much) I am thinking that this though, without a tuner, that the pcm is adjusting the air/fuel ratio because it thinks its getting exhaust gasses in, and this is causing a misfire condition. but buying a tuner just because will take up all my money i have left. from my experience with gas powered motors this is what im leaning towards, but i havent had enough time to see if unplugging it will change anything, plus im new to fords and how they operate computer wise. also i cleaned egr valve after they looked at it and it seems the codes disappeared. I am emissions exempt, and i dont care about a CEL so im not buying a tuner to just turn the light off

3. first time with a 2 piece driveshaft, the center support has some sort of a rubber bushing around it and i can move the driveshaft a bit, but there is no play in the bearing, just the rubber thing. EDIT: see bottom
4. dont know how it works with diesels, but a valve cover bolt is missing, previous owner stripped it out and i havent gotten to tapping it out yet, dont know if that will affect it

5. it has optima red tops, at the end of the night they have a 12.3v charge on voltmeter, in the mornings i notice they volts are down around 11v according to the gauge the previous owner put in.
EDIT: just checked, they were at 12.8v from driving all day, and they had a drop to 11.4v when cranking.

Any help is greatly appreciated, Im about done with this truck and im just going to sell it before i put more money in it. Im leaning towards number 2 right now with the egr cooler delete, but i cant afford something that isnt necessary right now.

EDIT: heres the rubber thing on the driveshaft, it can go up about 3/16" maybe more when i lift it.

If it helps, I just crawled under mine, it doesn't have hardley any movement in it.
Three more things, if you don't have a monitor, you really need one.......Write Up: Monitoring the 6.0L PSD.
I would suggest putting the stock air filter back in the truck, that is the one think ford got right the first time.
Do not take your truck back to the dealer you mentioned. Keep us updated.

I unplugged the egr valve and seems to have helped, but the vibrations been off and on, so well see over the next few days. I'll see if I can't wedge something in that carrier too and get it do it won't move. I seem to be noticing it more though that small bumps make the truck bounce a few times more than it should so I'm sure that the center support has something to do with it. Will report my findings.

I plan on getting a monitor and tuner, but once I get the money for it, I've already shelled out $2200 on a truck I just bought so I need to save up a little now if I can figure it out.

Does this truck have a two piece drive shaft? I'm assuming the photo to of the carrier bearing for a two piece shaft. I had a import truck with two piece shaft lost center u joint and carrier bearing at same time. Had one heck of a vibration when they went bad at about 50 MPH and above. Not thinking when I replaced u joints I forgot to mark drive shaft halves and got drive shaft out of balance and my vibration was still there. Took drive shaft to a shop and had it rebalanced all vibration went away.

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thanks for the insight guys, but i did find out it isnt the two peice driveshaft. it is an injector or two, or three. had a really cold morning and the vibration was really bad when the engine was still cold and driving. Just hoping I dont have to park overnight at the dealer to find out what injector(s) it is. Will be switching to Rotella T6 to see if thats enough to at least get me by until I can find time to leave it at the dealer.

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